Belt and pulley



V. R. CLARK BELT AND PULLEY Filed Dec. 24, 1938 INVENTOR. Vcfior J? C'czrk M, fizzy, 16 2M ATTORNEYS. a

Patented Oct. 8, 1940 UNITED STATES PATENT OFFICE- BELT AND PULLEY Victor B. Clark, Chicago, 111. U Application December 24, 1938, Serial No.247,55

1 Claim.

This invention relates to power transmission means, and has to do with a pulley and a belt cooperating therewith, for driving machinery and analogous purposes.

Pulleys are commonly made of iron, steel, hard wood or pressed'fibres and other dense materials. Leather belts used with such pulleys are formed from the hides of animals, in a known manner, and have a grain side and a flesh side.

The grain side of the leather is in the form of a. thin layer of fibres extending substantially perpendicular to the main or body portion of the leather. It is tight and substantially impervious to oil, to such an extent that tanners, when currying leather, always introduce the oils or greases used through the flesh side of the leather. The latter side of the leather is in the form of a relatively thin layer in which the fibres are disposed, in the main, lengthwise, from head totail,

go of the hide from which the belt leather has been out. It is known to provide pulleys with leather coverings or facings, cemented or riveted thereon. The leather facings thus applied are similar to belt leather and are disposed with either the flesh side or the grain side, usually the latter, for

contact with the belt.

In this country it is the universal practice to run leather belts with the grain side in contact with the pulley, and in European countries the usual practice is to run leather belts with the flesh side in contact with the pulley. The grain side is substantially impervious to oil, as above noted. The flesh side of leather, while it will absorb and retain oil, is not of sufficient thick- 5" ness or depth to permit ready displacement of such oil from the pulley contacting surface of the belt, by pressure incident to use of the belt, and quickly becomes compacted or matted down, taking on a gloss and becoming slippery.

With the grainside of the belt to the pulley, when the pulley becomes coated with oil or grease, as frequently occurs in machine shops and similar establishments, considerable slippage between the belt and the pulley occurs. This is objectionable for obvious reasons, as resulting in inefficient power transmission and subjecting the belt to excessive stresses and charring, due to heating by friction, greatly reducing the length of useful life of the belt. That is true whether the belt contacting surface of the pulley be formed of metal or other dense material, or of leather. In the latter case, if the grain side of the leather on the pulley is the belt' contacting surface thereof, the slippage will be about as great as if the I pulley surface were metal. If the belt contacting (Cl. T L-230.7)

surface of the pulley isithe. flesh side of the leather, it quickly becomes matted down, and slippage occurs.

When the belt is runwith the flesh side to the pulley, that side absorbs oil, and quickly mats down, coating the pulley with oil, and slippage occurs .as. before. It makes little difference whether the belt contacting surface of the pulley be formed of metal or other dense material, or of leather. In-the latter case, if the belt con- 10 tacting'surface of the pulley is the grain side of the leather, the slippage will be substantially as great as if the pulley surface were metal. If the belt contacting surface of the pulley be the flesh side. of the leather, it 'quickly mats down 15 and considerable slippage occurs, though it may be less than that which occurs in any other of the cases mentioned. In any of the cases above referredto, grease or oil on the pulley, in ap- I, preciable amount, causes considerable slippage, 20 with resulting decreased efficiency in power transmission and shortening of-the life of the belt. It is generally recognized, for that reason, that the presence of any-considerable amount of grease or oil on belt driven pulleys should be 25 avoidedand, so far as possible,- precautions are taken to that end, though often with little success.

My invention is directed primarily to the provision of an improved pulley and belt cooperating 30 in a novel manner so as materially to reduce, or completely eliminate, objectionable slippage between the pulley and the associated belt. More specifically, I provide a pulley anda belt each having a contacting surface of such character as 35 to be readily saturated by oil, but of resilient loose fibrous structure such as to permit instantaneous displacement or egress of the oil from the contact surfaces, when the latter are subjected to belt pressure, such surfaces being wear resistant and of sufiicient firmness substantially to retain their shape'under'operating belt tension. Excess oil is thus squeezed out of and dissipated from the contacting surfaces of the belt and the pulley, formation of an oil fllm is prevented and slippage between the belt and the pulley, even under abusive conditions of operation, does not occur, the presence of a considerable amount of oil on the belt and the pulley be- 50 ing advantageous, as increasing the traction thereof, as will appear later. This permits of lower operating belt tension with corresponding reduction in bearing pressures, and increased life of the belt. Further objects and advantages 55 of my invention will appear from the detail description.

In the drawing:

Figure 1 is a fragmentary plan view of a strip of leather such as that used in the belt and pulley of my invention, as viewed from the grain side;

Figure 2 is a fragmentary sectional view taken substantially on line 2-2 of Figure 1;

Figure 3 is a sectional view similar to Figure 2, but after the leather strip has been leveled off;

Figure 4 is a sectional ,view taken substantially on line 4-4 of Figure 2;

Figure 5 is a side view of a pulley embodying my invention;

Figure 6 is a front view of the pulley of Figure 5, with a belt embodying my invention applied thereto, the belt being shown in section and the pulley being shown partly in section substantially on line 6-6 of Figure 5;

Figure '7 is a plan view of a modified form of pulley embodying my invention;

Figure 8 is a sectional view taken substantially on line 88 of Figure 7, showing, in transverse section, a belt embodying my invention applied to the pulley; and

Figure 9 is a side view, on a reduced scale, of the pulley and belt of Figure 8, with the belt broken away.

This application is a continuation in part of my co-pending application for Pulley, Serial No. 186,956, filed January 26, 1938.

It will be helpful to an understanding of my invention to consider first, briefly, the fibre structure of the leather which I employ. Figures 1 and 2 may be considered as illustrating, more or less diagrammatically, the structure of a strip of leather cut from an ox hide lengthwise thereof, in accordance with usual practice, such as is commonly used in leather belting. This strip, designated L, may be considered as comprising a main or body portion a, a relatively thin grain side layer b and a flesh side layer 0 of slight thickness relative .to body portion a. The grain side b is composed of fibres extending substantially perpendicular to body portion a and not tightly attached thereto, as is evidenced by what is known as piping when the leather is bent on a small radius with the grain side in, causing separation of some of the fibres of the grain layer b from the body portion a. The body portion a, which comprises by far the major thickness of the leather, is composed of a mass of interwoven fibres more or less indiscriminately disposed, many of which extend transversely of the strip L as viewed in Figure 1, the cut ends of these latter fibres being indicated by the stippling in Figure 2. The flesh side layer 0 may be considered as composed of a relatively thin layer of fibres which are, in general arranged in parallelism and extend lengthwise, from head to tail, of the hide from which the strip was cut.

I shall describe first the pulley of my invention.

In constructing the pulley of Figures 5 and 6, I cut a plurality of discs I0 from a suitable piece of leather, these discs being cut perpendicular to the grain and the flesh sides. For purposes of description, it may be considered that the discs are cut from the grain side to the fiesh side of the leather, although they may be cut in the opposite direction so far as the direction in whichthe cutting operation progresses is concerned, it being immaterial from which side of the leather the cut is initiated. It will be seen that by cutting the discs in this manner, the internal fibres of the leather, particularly the fibres comprising the body portion a thereof, are exposed at the edges of the discs. In Figure 6 I have shown four discs I0, cut from leather in the manner stated, mounted upon an annular core ii, formed of metal, this core defining a cylindrical opening or passage the ends of which register with openings [2 through the discshaped clamping plates !2 secured together and to discs E E] by means of rivets l3, or in any other suitable manner. The leather discs ID are thus clamped together under pressure between the plates l2 and, if desired, may also be secured together, and secured to plates l2 and core H, by an appropriate adhesive or cement, although ordinarily this is not necessary. After the parts of the pulley have been assembled in the manner stated, the discs 10 may be cut, from their outer circumference, to provide a Vshaped groove M, the pulley thus formed being intended for use with a V-belt. Conveniently, core H and clamping plates [2 may be provided with aligned grooves defining a keyway Hi. In the pulley thus produced the belt contact surface is formed by the body portion a, of the respective discs ill, in major portion, and the body fibres of these discs are cut across, in considerable portion, so that the ends of such fibres provide a highly efficient friction surface having a high coefiicient of friction. Further, the body a of the respective discs, composed of the fibres referred to, is of considerable depth, and, while easily saturated with oil, is loose and resilient in structure to such extent that when the belt contact surface is subjected to belt pressure, the oil is immediately displaced from the pulley contact surface into the bodies of the leather discs. This eliminates possibility of forming an oil film between the belt and the belt contact surface of the pulley, assuring a high coefiicient of friction between such surfaces and preventing objectionable slippage therebetween.

If the discs E0 of the pulley of Figures 5 and 6 are to be cemented together, the grain side layer b of the respective discs should be removed, in order that the adhesive or cement may penetrate into the leather of the discs.

When constructing pulleys of moderate or large diameter, the use of discs, as in Figures 5 and 6, may be open to the objection of expense due to the use of so much leather. That objection may be avoided, where desired, by forming the leather facing of the. pulley from a suitably wound leather strip, cut similarly to the leather strip of Figures 1 and 2, but leveled ofi and of adequate length. Such a pulley is illustrated in Figures 7 and 8. It comprises a two-part core formed in two sections l8, which may be formed of wood, with a metal ring 19 therebetween and projecting radially outward therebeyond to a suitable extent. Two leather strips 20 are wound upon core sections [8 in opposite directions, from ring it, the end portions of these strips tapering to feather edges, as will be clear from Figure '7, and these strips forming oppositely disposed spirals about core sections i8. Each strip 2|] is wound edgewise, with one cut edge thereof seating upon core section I8 and its other out edge exposed to provide the belt contact surface of the pulley. The strips 20 eachform a plurality of thicknesses of leather, lengthwise of the pulley, and are clamped between the center ring l9 and end clamping plates 2|, the latter being secured together and to the core of the pulley by elongated rivets 22, or in any other suitable manner. Wound strips 20 of leather are thus confined under pressure between plates 21 and ring l9. Sections l8 and ring IQ of the pulley core, and clamping plate 2|, are provided with aligned openings together defining a shaft opening, the pulley being also provided with an appropriately disposed keyway or slot 23. Preferably, in use, the direction of rotation of the pulley of Figures 7 and 8 is such as to tend to wind the strips 28 more tightly about the core sections l8, and the pulley may bear a suitable, marking to indicate the direction in which it should rotate in use. If desired, the windings of the respective leather strips 20 may be cemented to each other and to the core and the clamping plates of the pulley, although this is not essential. The belt contact surface of the pulley of Figures '7 and 8 possesses the advantages and characteristics of the belt contact surface of the pulley of Figures 5 and 6, and need not be described in greater detail.

In preparing the leather strips for forming the pulley of Figures 7 and 8, these strips are leveled off, to assure close and accurate contact of the adjacent convolutions thereof when they are wound spirally onto the sections of the pulley core. This levelling off results in removing the grain side layer of the leather, for the major portion of or the full depth thereof, indicated by line l@ of Figure 2, as well as removal of the fiesh side layer to an appreciable depth, indicated by line d-d of Fig. 2. The strip, after levelling off thereof, is shown, in lengthwise section, in Figure 3. Since the grain side layer has been removed from the strip, the adjacent convolutions thereof, when it is wound spirally on the core section of the pulley, may readily be secured together by a suitable adhesive or cement, if desired.

From what has been said, it will be seen that, in both forms of my pulley herein disclosed, the belt contacting portion thereof is formed of the interior body fibres of the leather, will readily absorb oil so as to be saturated thereby, and is of considerable depth and such character that excess oil is readily displaced from the belt contact surface, by belt pressure. That prevents formation of an oil film upon the belt contact surface of the pulley and eliminates slippage between the pulley and the belt from that cause.

The pulley of my invention cooperates with the belt of my invention, which I shall now describe, in a novel manner to prevent formation of an oil film between the contacting surfaces of the pulley and the belt. In Figure 6 I have shown, in transverse section, a V-belt 24 of leather as applied to the pulley of that figure. The belt is shown, for purposes of illustration, as formed from a single thickness of leather comprising the fiesh side layer 0, disposed outward, and the body portion a, in contact with the body portions of the discs ii the grain side layer of the leather having been removed. Many of the fibres of body a of belt 241 are substantially perpendicular to the inclined side surfaces thereof, which assures maximum frictional contact between the belt and the pulley, with increased efficiency in power transmission. The body a of the belt will readily absorb oil so as tobe saturated thereby, but is of considerable depth and sufficiently porous so that excess oil is readily displaced from the pulley contacting surface of the belt into the body thereof, by belt pressure. That eliminates possibility of an oil film, such as would cause slippage between the pulley and the belt, forming upon the pulley contacting surface of the latter. In that manner, the pulley and the belt cooperate to provide maximum tractive effect therebetween while effectively preventing slippage. The fact that the discs in of the pulley may retain thereon the grain side layer and the flesh side layer is not objectionable in most cases, since the total exposed area of these layers is slight relative to the total exposed area of the interior body portions of the discs 10 and belt 24, into which the oil is displaced, by belt pressure, from the contact surfaces of the pulley and the belt. In practice, the belt 24 may, of course, be formed of more than one thickness of leather, cut so as to expose the fibrous interior body portion of the belt leather for contact with the pulley.

In Figures 8 and 9 I have shown a fiat leather belt 24a, embodying my invention, as used with the pulley. This belt is shown as formed of a single thickness of leather with the flesh side layer 0 disposed outward. When constructing the belt 240 the grain side layer b of the leather is removed for the full depth thereof, as indicated by line d4 in Figure 2. This exposes the fibrous interior body portion a of the leather, composed of a mass of interwoven fibres more or less indiscriminately disposed, many of which extend with their cut ends perpendicular to the exposed surface of the leather, as indicated by the stippling in Figure 4. This surface of belt 24a is disposed in contact with the leather strips 20 comprising the belt contacting portion of the pulley, the cut ends of the fibres of the body portion a of strips 20 being disposed substantially perpendicular to the exposed cut edges of the strips. In this manner, I assure maximum frictional contact and tractive effect between the belt and the pulley. Further, the body a of the belt and the body a of the respective strips 29 is porous and resilient, and of considerable depth, such that oil contained therein is readily displaced, by belt pressure, from the contacting surfaces of the belt and the pulley. That eliminates possibility of formation of an oil film between the pulley and the belt, avoiding possibility of slippage from that cause. While belt 24a is shown as formed from a single thickness of leather, for purposes of illustration, it may be formed of two or more thicknesses of leather, as conditions may require, suitably secured together.

Contrary to accepted practice, the presence of oil in considerable quantity on the pulley or belt is not objectionable, in the belt and pulley combination of my invention, but is advantageous as contributing to the efliciency thereof and the prevention of slippage. That is due to the fact that the interior fibrous body portions of the leather of the belt and the pulley are in contact, so that oil is displaced from between the contacting surfaces of the belt and the pulley, by belt pressure, the oil present in the belt and the pulley serving to maintain the body portions thereof in a more or less softened and flexible condition which assures close contact between the surfaces of the belt and the pulley. Experience has demonstrated that, in many instances, where the oil has dried out to a certain extent, from either the belt or the pulley, the efliciency of the belt and pulley combination is increased by squirting a considerable amount of oil upon the belt and the pulley. There is no risk of getting so much oil upon either the belt or the pulley that objectionable slippage therebetween will result, since any oil not absorbed within either the belt or the pulley is displaced or squeezed from the contacting surfaces thereof, by belt pressure, and the excess oil is discharged from the rotating pulley by centrifugal force.

An important feature of my invention, therefore, is that the presence of a considerable amount of oil upon either the pulley or the belt is not objectionable but, to the contrary, actually increases the efiiciency of the combination. In that respect, the belt and pulley combination of my invention attains new and unexpected results with respect to the present practice, it being generally recognized that in using leather belts and pulleys of ordinary type the presence of oil or grease upon either the pulley or the belt, in any considerable quantity, will cause slippage and materially reduce efficiency.

While the belt 24a is shown as formed of leather the grain side layer of which has been removed, it may be formed of leather having the flesh side layer removed and retaining the grain side layer. In such case, however, the grain side layer of the belt should be disposed outward, with the fibrous body portion a of the belt leather contacting the pulley. Obviously, if desired, the belt 24a may be formed of leather having both the grain side layer and the flesh side layer removed.

Tests made with the belt and pulley combination of my invention have demonstrated conclusively the superiority thereof over pulleys and leather belts of ordinary type, such as used in accordance with present practice. A brief statement of one of these tests will sufiice. A leather belt of ordinary type, having a width of 1", installed on the ordinary iron or steel pulley, under a tension'of 5 lbs., will build up a tight side tension of eight (8) pounds before it will slip, when the pulley is in a clean and dry condition free from oil or grease. That, in such a combination, means that the effective pulling power is 3 pounds. The same belt, but with the flesh side layer of the leather removed, installed on the pulley of my invention, with the exposed surface of the interior body portion of the belt leather in contact with the interior body portion of the leather of the pulley, and the contacting surfaces of the pulley and the belt containing oil in considerable quantity, when under 5 lbs. initial tension, will build up a tight side tension of 40 lbs., thus giving a pulling power of 35 lbs. In other words, by the pulley and belt combination of my invention I render it possible to obtain a pulling power approximately eleven times as great as that which is possible when using a belt of the same width, but of the ordinary type of leather belt, with an iron or steel pulley in accordance with the usual practice. The advantage is obvious. A further advantage is that, as previously noted, the presence of oil in considerable quantity upon either the belt or the pulley of my combination in nowise detracts from the efficiency thereof but, to the contrary, is conducive to maximum efficiency.

While the belt of my invention is preferably formed of leather, and the belt contacting portion of the pulley also is formed of leather, both so made that the fibrous interior body portion of the leather provides the contacting surfaces between the belt and the pulley, my invention comprehends, within its broader aspects, the use of other suitable materials having the above referred to characteristics of leather;

I claim:

In combination, a pulley having an outer layer of leather With the interior fibrous body portion of the leather exposed and providing a belt contact surface comprising the fibres of said body portion, the pores of said body portion of the leather being substantially open and unobstructed for an appreciable depth from said belt contact surface whereby liquids may readily be displaced by belt pressure from said belt contact surface into the body of said layer of leather, and a leather belt having the interior fibrous body portion of the leather thereof exposed and in driving contact with the belt contact surface of said pulley, the pores of the body portion of said belt being substantially open and unobstructed for an appreciable depth from the pulley contact surface of said belt whereby liquids may readily be displaced by belt pressure from said pulley contact surface into the body of the leather of said belt, the pulley and the belt cooperating to permit ready displacement of liquid from between their contacting surfaces and thereby preventing formation between such surfaces of a liquid film of a character to cause objectionable slippage between said pulley and said belt.

VICTOR R. CLARK. 

